upper arm/thigh weakness

From another post here (sorry, forgotton who), I found out this was a thyroid symptom - specifically hyperT. At my worst, I get this a lot (this past week I couldn't even hold up a book, or my arms would start shaking) - all my other symptoms are hypo. Could this be a hypoT symptom as well? Is there another reason I might be getting this that isn't thyroid related?

While I'm at it - there was a thread a while back about linking increased symptoms with certain phases of the menstrual cycle - has anyone changed their dosage appropriately, or do we just suffer through the down times??